We all know that automatic transmissions have torque converters, and that they are supposed to multiply the torque that is input to them. All converters have a stall speed, and that speed can vary by the size and type of the converter, engine torque input, etc. From what I have heard and read, most factory converters have a stall at around 1400-1800 RPM. Some of the higher performance aftermarket converters go well up into the 4000+ RPM range. Here is my question. Let's say that you have a stock car/engine, and the torque converter stall speed is 1700 RPM. If you increase the amount of torque that the engine puts out(ie nitrous, boost, etc.) would the stall speed of the converter change based on the amount of torque that is being input to it?
Trying to become the most modded out N/A 2nd gen sunbird 4 cylinder on the org with a..... screw that, I'm going turbo!!!
2.Slow OHC I4
Ported cylinder head, intake and exhaust
Relocated IAT with a custom WAI with a 6x9 K&N conical filter
All this, and I still can't go fast.............yet!!
i'm not completely sure of this, but from my rebuild the way it was explained, is that other things wont raise the stall speed.... it will reach it and then sit there...but sitting there can overheat the tranny....
one the converter is damaged though it can raise or lower that speed depeding on the damage.
Yes, the more power your engine has the more RPM differential you can have between the engine and the transmission.
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i dont see how your power output can effect the stall speed. its the strator blade angle that does that.
since the torque coverter multiplies torque while in stall by a factor of 2-ish, it seems to me increased torque in the 2000 rpm range would only put more strain on your tranny while in gear.
what i'd like to know is if increasing the fluid pressure affects stall speed and/or cruising efficency?
Listen F***ers. FASTERTHANAHONDA is a joke because I WORK FOR HONDA. I'll talk @!#$ about Fords to, that doesn't mean I can beat a 12 second mustang.
ok, first off the stator blade is INSIDE of the torq converter and is a working part of the torq converter
the amount that torq that is multiplied by the torq converter is different in all applications. however most are about 1.1-1.3.
here is a quick rundown on how a tq converter works
you have the body of the converter that attaches to the flywheel and the snout attaches to the trans fluid pump inside the trans. so when the motor is running the trans pump is always turning. then you have the stator inside the converter. this is what you trans input shaft conects to.
the converter body has fins on it, and the stator has its own fins. as the engine turns the converter, wich turns the pump, fluid is pumped inside the converter. this fluid runs along the fins ofthe conveter body and is thrown against the stator fins. as the engine increases rpm the velocity of the fluid thrown against the stator will increas and eventually there will be enough velocity against the stator to make it move, thereby turning the input shaft and moving the car. this is what is known as stall speed. when the stator speed equals converter speed. the torq multiplication takes place when you are just below stall speed and ends when you reach it. this allows the carto move from a standstill with little throttle during normal driving.
becouse this is a fluid coupling the actual stall speed experience has everything to do with torq applied and resistance created by the weight of the car, friction of the tires, gear ratio, and efinciecy of the trans itself. therefore, stall advertised is more of a guidline than anything else. it gives you an idea of aboutwhere it is designed to stall.
I hope this helps
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when you beat someone in a civic people wine and make excuses
when you beat someone in a cavalier they pull over and check under thier hoods
and to awnser the question stated at the top....
yes....assuming that the poser increase comes when you are about to cross the converters stall threashold
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when you beat someone in a civic people wine and make excuses
when you beat someone in a cavalier they pull over and check under thier hoods
i quoted wikipedia that it was something like 1.5-2.3 depending on application. lesson learned. lol
so if the stall speed is where the engine starts to move the car...i dont get why i can idle down my street so i dont wake up the neighborhood every night? or why i can start accelerating at 1200 rpm? does that mean the torque is being multiplied all the way up to 2375 (4T40E)? and does that mean after that, all the extra speed of the input to the output is just parasitic power loss?
sorry, but i gotta ask/learn sometime.
Listen F***ers. FASTERTHANAHONDA is a joke because I WORK FOR HONDA. I'll talk @!#$ about Fords to, that doesn't mean I can beat a 12 second mustang.
remeber, it is a fluid coupling. stall speed experienced is dependant on torq applied vs. resistance on the stator. so just the amound of you idoling with your food off the break is enough to move your car. however, you are not at that 1-1 converter/stator ratio yet that is stall speed.
you already know what happens when you idol with the breaks off. now put the breaks on and rev the motor. the cars breaks have supplied the resistance that will force the converter to a higher stall. you will notice that you will rev to a point where you simply cannot rev any more without moving the car. now you are very close to the stall speed, close enough to the point where the resistance of the breaks hold back the motor, instead of the motor pushing the car. this rpm however, is NOT you stall speed becouse you are not at 1-1. the breaks are forcing the converter to stall at a different speed. unless you have enough power to overcome the breaks that is.
rember, not mechanical coupling, fluid coupling. so as long as the tork converter body is throwing fluid against the stator the the car will at least try to move. weather or not you are at that 1-1 ratio yet.
there in lies an old trick called flashing the converter. when launching, assuming you have good traction, you can get the converter to stall at a slightly higher than normal. one foot on the break, one foot on the gas, hold down the break and give it just enough rpm so you are near where the car wants to move. not as HIGH as you can rev it cause then all you will do is put undue stress on the trans until the light turns. a split second before the light turns green, stomp the gas. and when the green comes sidestep off the break. if you time it right you should be hitting wot and the break should be off right when the green comes on. becouse of the resistance of the breaks you will force a higher stall speed, and will land right in that 1.1 - 1.3 or whatever tork multiplication zone. and since you timed it so good this will happen right when you are letting off the break so now you are actually using that tork multiplication to make you go foreward instead of sitting there amking your trans hate you for revving it up with the break down.
this takes practice to find the "sweet spot" on your car
if I get to complicated just tell me. my dad tried to teach me how an out works by using cutaway diagrams when I was very young and that @!#$ was confusing as all hell until I learned it my own way.
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when you beat someone in a civic people wine and make excuses
when you beat someone in a cavalier they pull over and check under thier hoods
i think im starting to get it now. i need to let it all soak in now. lol
thanks for writing all that.
ill praise whoever makes a sticky write up about the auto trany with info like this.
Listen F***ers. FASTERTHANAHONDA is a joke because I WORK FOR HONDA. I'll talk @!#$ about Fords to, that doesn't mean I can beat a 12 second mustang.
tq from the motor will raise or lower the stall speed to a point , it was a old trick back in the 70's to take the tq from the 4cyl vega and put it behind a V8 , for use as a higher stall tq converter for a low $$$ amount , the stall speed would raise from roughly 1500 to 2500-3000
but being the tq converter wasnt made to hold the power from the bigger V8's it didnt last long , and was better for temp use in a drag car
my 2.4 stalled between 2000-2500 , and once the tq management was turned off i was seeing just over 3000
